What -- in basic terms -- is encryption?
Encryption is a way that employs a cryptographic algorithm (procedure) to disguise or hide a message (where a message could be a letter, a document, a whole disk image on a computer -- any string of data).
A cryptographic algorithm is a procedure that takes plaintext data (unencrypted, readable) and transforms it into ciphertext (hidden,
disguised) in a reversible way.
A simple example of an encrypted message:
Gurl unir rlrf gb frr ohg qb abg frr naq rnef gb urne ohg qb abg urne.
You can decrypt it (decryption is the opposite of encryption) if I tell you the key: It is a simple letter substitution, where the alphabet is offset by 13 places. A gets replaced by N; B by O; and so on.
This was first published in March 2001